The increase in net negative surface charge of leukemic cells suggested that normal leukocytes could be antigenically modified by making them more electronegative by tagging them with l-fluoro-2-4- dinitrobenzene. In preliminary studies with rabbits it was observed that l0,000 molecules of DNFB per cell was optimum for eliciting the production of antibodies which had specificity for human leukemic cells and minimal cross reactivity with normal WBC s. We plan to evaluate the diagnostic usefulness of antisera against DNP-tagged WBC's by testing them against cells obtained from patients with acute and chronic lymphocytic and myelocytic leukemia using leukoagglutinin and cytotoxic antibody assays. The sera also will be tested against normal human WBC's, DNP-tagged normal and leukemic WBC's and WBC's obtained from patients with either nonmalignant or pre- malignant myeloproliferative and lymphoproliferative disorders in order to establish if they can be used as reagents for the serologic diagnosis of leukemia. We propose to investigate the immunobiologic properties of DNP- tagged leukocytes using lectins as molecular probes. The mitogenic response of DNP-tagged cells to Concanavalin A, Phytohemagglutinin and Pokeweed mitogen will be assessed by their ability to incorporate 3H- thymidine. Mixed lymphocyte culture reactivity of DNP-tagged versus untagged cells will be investigated and should provide data on the ability of tagged WBC's stimulate a T cell mediated immune response. Scanning electron microscopy will be used to study the surface membrane properties of DNP-tagged normal and malignant lymphocytes and granulocytes. Finally, we plan to develop a combined chemotherapy-immunotherapy model initially employing the lymphoma L 1210 in DBA/2 mice and the myelocytic leukemia C 1498 in C57BL/6 mice. Tumor-specific cell mediated immunity will be studied using the chromium-51 and technetium- 99m microcytotoxicity assays. These studies should establish whether DNP-tagged cells can be used effectively for immunotherapy.